Data Size Converter

Your client says the video is '2.5 GB' and your S3 dashboard says it's 2,684,354,560 bytes. Same file, two different numbers, and you need to confirm they match before invoicing. Type the value in either unit and the others fill in.

The converter handles both binary (KiB, MiB — powers of 1024) and decimal (KB, MB — powers of 1000) units. Storage manufacturers use decimal because the numbers are larger; operating systems use binary because the math is cleaner. Knowing which is which prevents arguments.

Goes from bytes all the way up to petabytes. If you're working in zettabytes, you've outgrown this tool.

The conversion math is mechanical: every step in binary is a factor of 1024 (2^10), and every step in decimal is a factor of 1000. So 1 KiB = 1024 B, 1 MiB = 1024 KiB = 1,048,576 B. In decimal, 1 KB = 1000 B, 1 MB = 1,000,000 B. By the time you reach terabytes, the gap between binary and decimal interpretations is roughly 10% — which sounds small but is the difference between a '1 TB' drive label and the 931 GiB your operating system reports.

The historical confusion has a real culprit. Disk manufacturers settled on decimal early because larger numbers sell drives. RAM manufacturers and operating systems use binary because memory addressing is naturally a power of two. The IEC standardized binary prefixes (KiB, MiB, GiB) in the late 1990s precisely to disambiguate this, but adoption has been spotty — Linux generally uses the binary prefixes, macOS switched its display to decimal years ago, Windows still shows binary numbers labeled with decimal prefixes, which is the worst of both worlds.

A worked example: you receive a delivery confirmation that says '4.7 GB Blu-ray ISO.' Decimal interpretation: 4,700,000,000 bytes. Binary interpretation: 5,046,586,572 bytes (4.7 × 1024^3). Which is right? Optical media manufacturers use decimal, so the file is around 4.7 × 10^9 bytes. Your file system might display this as '4.38 GB' (binary), making it look smaller than advertised. The disc isn't broken; the display is just using a different prefix interpretation.

For network speeds the conversion gets one extra wrinkle: bits versus bytes. A 100 Mbps connection moves 100 megabits per second — that's 12.5 megabytes per second. You'll see networks consistently quoted in bits and storage consistently quoted in bytes, and downloads display as bytes per second, so a 100 Mbps line downloading a 1 GB file takes about 80 seconds, not 10. This is the single most common source of 'why is my download so slow' confusion.